Questions tagged [integer]
For challenges involving the manipulation of integers.
292
questions
30
votes
5answers
2k views
Make The Finest Magic Code Square
In math a magic square is an N×N grid of numbers from 1 to N2 such that every row, column, and diagonal sums to the same total. For example here's a 3×3 magic square:
In this challenge we'...
2
votes
14answers
2k views
Move my liquid to make me equal
You are given 4 positive integers: volume of the first container (v1), volume of the second container (v2), volume of the liquid ...
18
votes
9answers
1k views
Proportion of self-avoiding walks on a square lattice
The challenge
Given a positive integer N, compute the proportion of N-step walks on a plane that don't intersect themselves.
...
20
votes
38answers
4k views
Round up my number
Sandbox
Given two positive integers a and b, return the smallest multiple of b that is greater than or equal to a.
Examples
Definitions: true = ...
15
votes
16answers
912 views
Find the length of a number's “base-jumping” path
Consider a positive integer N written in base b. A sequence is generated from this number by finding the largest digit ...
23
votes
8answers
2k views
Inverse Look-and-Say
Background
The Look and Say Sequence is built up by reading off the digits of previous entries in the sequence, counting the number of digits in groups of the same digit. For example:
...
0
votes
0answers
68 views
Making Fibonacci Cry [duplicate]
Introduction
The Fibonacci sequence is a mathematical sequence in which each term is the sum of the \$2\$ terms before it; the first two terms are \$0\$ and \$1\$. The first few terms are \$0, 1, 1, ...
0
votes
20answers
456 views
Quine in Bytes, not Characters [duplicate]
Introduction
A quine is a program that takes no input and produces a copy of its own source code as output. Writing a quine is a standard test of a programming language. Most quines operate using ...
18
votes
25answers
4k views
Visualize a large int
Convert a large int (e. g. 1234567890) into a string containing the usual decimal prefixes k, M, G, T, etc. for kilo, mega, giga, tera, etc. The result shall be groups of three digits, interspersed ...
12
votes
35answers
2k views
Determine the Winner of a Game of Australian Football
In Australian Football, goals are worth 6 points and behinds are worth 1 point. Scores may include the number of goals and behinds, as well as the total score. Given the number of goals and behinds ...
31
votes
29answers
5k views
Double it your way
There have been a couple of challenges involving doubling source code: here and here. The task we have here is a bit harder, but should be doable in almost every language.
In this challenge, you will ...
26
votes
17answers
4k views
Infinitely many primes
Since Euclid, we have known that there are infinitely many primes. The argument is by contradiction: If there are only finitely many, let's say \$p_1,p_2,...,p_n\$, then surely \$m:=p_1\cdot p_2\cdot.....
22
votes
24answers
4k views
Count the number of triangles
Given a list of positive integers, find the number of triangles we can form such that their side lengths are represented by three distinct entries of the input list.
(Inspiration comes from CR.)
...
18
votes
30answers
2k views
Numbers Decrease while Letters Increase
Randomly inspired by Numbers Increase While Letters Decrease
Given a list of mixed letters and integers (e.g., ['a', 2, 3, 'b']) increase the letters by one ...
26
votes
30answers
3k views
Output with the same length always
With challenges like Output with the same length as the code and Create output twice the length of the code, I thought of a separate, but similar challenge.
The task is to produce an output. It can ...
13
votes
1answer
303 views
Decompose Commutators
A theorem in this paper1 states that every integral n-by-n matrix M over the integers with trace M = 0 is a commutator, that means there are two integral matrices A,B of the same size ...
34
votes
35answers
5k views
Repeated! Factorials!
Not to be confused with Find the factorial!
Introduction
The factorial of an integer n can be calculated by
$$n!=n\times(n-1)\times(n-2)\times(...)\times2\times1$$...
28
votes
29answers
4k views
Inverse Colombian Function
Let's define a sequence: The n digit summing sequence (n-DSS) is a sequence that starts with n. If the last number was k, then the next number is k + digit-sum(k). Here are the first few n-DSS:
...
5
votes
4answers
437 views
Find X,Y,Z coordinates from index
Introduction
I began studying the Collatz Conjecture
And noticed these patterns;
0,1,2,2,3,3...A055086, and 0,1,2,0,3,1...A082375,
in the numbers that go to 1 in one odd step,
5,10,20,21,40,42......
23
votes
24answers
3k views
Robbers: The Hidden OEIS Substring
This is a Cops and Robbers challenge. This is the robber's thread. The cop's thread is here.
The cops will pick any sequence from the OEIS, and write a program p that prints the first integer from ...
37
votes
27answers
4k views
Cops: The Hidden OEIS Substring
This is a Cops and Robbers challenge. This is the cop's thread. The robber's thread is here.
As a cop, you must pick any sequence from the OEIS, and write a program p that prints the first integer ...
26
votes
54answers
6k views
Integer Lists of Noah
Introduction:
I think we've all heard of it, but here a very brief summary: Noah gathered two of every species of animal on the planet, male and female, to save in his Ark during a great flood. The ...
2
votes
3answers
116 views
Sum of multiples of powers of ten of an integer [duplicate]
Write a function to produce, for a non-negative integer, a string containing a sum of terms according to the following:
...
-6
votes
4answers
195 views
Is this number a palindrome? [closed]
Input
A single integer in your language's preferred format. This format is non-negotiable (no input as strings, arrays of digits, etc.), but standard I/O formats do apply if otherwise it would be ...
37
votes
31answers
14k views
Do the 26 richest billionaires own as much wealth as the poorest 3.8 billion people?
Introduction:
A few days ago I read this post with the same title when I came across it in the HNQ. In this question it is being discussed if the claim of president-candidate Bernie Sanders, who ...
44
votes
12answers
3k views
Prime parity peregrination
The purpose of this challenge is to graphically depict a walk on the plane, where the direction of each step \$k\$ is determined by the primality of \$k\$ and the parity of its binary expansion. ...
5
votes
0answers
192 views
Fastest way to iterate over sublattice of discrete lattice
I need to construct a functor that iterates over the linear representation of a sub-lattice of size \$d_x,d_y,d_z,d_q\$ embedded in a lattice of size \$n_x,n_y,n_z,n_q\$. The sub-lattice corner is ...
21
votes
6answers
1k views
Subtract the Folded Matrix
Challenge:
Given an NxN matrix where \$N\geq2\$ and one of eight distinct 'folding options', output a 2D array/list with the subtracted values.
The eight folding options are: left-to-right; right-to-...
11
votes
6answers
917 views
Group Integers by Originality
Introduction:
I collect twisty puzzles. Most twisty puzzles are produced and sold by Chinese companies. Most well-known companies ask permission from puzzle designers to produce their designs and ...
20
votes
22answers
2k views
Rotated Position of Integers
Challenge:
Input:
A sorted list of positive integers.
Output:
The amount of integers which are still at the exact same index, after rotating the digits in each integer its index amount of times ...
8
votes
4answers
610 views
Leading and Suffering Numbers
Introduction:
In Dutch, the words leading and suffering, being 'leiden' and 'lijden' respectively, are pronounced the same way. One is written with a "short ei", and one with a "long ij", as we ...
20
votes
9answers
1k views
Warped chessboard
This challenge is about building a chessboard in which the square size, instead of being constant across the board, follows a certain non-decreasing sequence, as described below.
The board is defined ...
32
votes
21answers
2k views
A Note on N!
J. E. Maxfield proved following theorem (see DOI: 10.2307/2688966):
If \$A\$ is any positive integer having \$m\$ digits, there exists a positive integer \$N\$ such that the first \$m\$ digits of \$...
-2
votes
6answers
251 views
Map values to any multidimensional array [closed]
Codegolf challenge - mapping values in a multidimensional array
[
[0, 0, 0],
[0, 0, 0],
[0, 0, 0]
]
This 2D array is sick of being so false, and wants to ...
23
votes
20answers
2k views
Maximum summed subsequences with non-adjacent items
Introduction:
Inspired by these two SO questions (no doubt from the same class): print the elements in the subarray of maximum sum without adjacent elements java and Maximum sum of non adjacent ...
11
votes
6answers
1k views
Area of a 2D convex hull
You are given an array/list/vector of pairs of integers representing cartesian coordinates \$(x, y)\$ of points on a 2D Euclidean plane; all coordinates are between \$−10^4\$ and \$10^4\$, duplicates ...
27
votes
13answers
3k views
Valid Badminton Score?
Introduction:
I saw there was only one other badminton related challenge right now. Since I play badminton myself (for the past 13 years now), I figured I'd add some badminton-related challenges. ...
26
votes
22answers
2k views
The Digit Triangles
Challenge:
Input: A positive integer \$n\$
Output:
Create a list in the range \$[1,n]\$, and join it together to a string (i.e. \$n=13\$ would be the string ...
32
votes
23answers
8k views
Could you please stop shuffling the deck and play already?
Challenge:
Input: A list of distinct positive integers within the range \$[1, \text{list-size}]\$.
Output: An integer: the amount of times the list is riffle-shuffled. For a list, this means the ...
14
votes
11answers
907 views
Source permutation
A permutation of a set \$S = \{s_1, s_2, \dotsc, s_n\}\$ is a bijective function \$\pi: S \to S\$. For example, if \$S = \{1,2,3,4\}\$ then the function \$\pi: x \mapsto 1 + (x + 1 \mod 4)\$ is a ...
11
votes
31answers
829 views
Sum integers in a string
Input
A string.
Output
The sum of all integers in the line.
Constraints
1≤Length of line≤500
Sample test Case
Input
the 5is 108 seCONd4 a
Output
...
33
votes
5answers
8k views
Historical difference between `/` and `÷` in mathematical expressions
Introduction:
Inspired by a discussion that is already going on for many years
regarding the expression \$6÷2(1+2)\$.
With the expression \$6÷2(1+2)\$, mathematicians will quickly see that ...
7
votes
7answers
545 views
Check type of an integer
You will receive an integer less than 2000000000 and bigger than -2000000000 and you have to test what type(s) of number this is out of:
...
4
votes
9answers
290 views
Floating over the integers
As you may know, the typical binary floating point numbers in a computer language are quite different than the typical integer numbers in a computer language. Floating point numbers can represent a ...
20
votes
17answers
2k views
Square Root Distance from Integers
Given a decimal number k, find the smallest integer n such that the square root of n is ...
19
votes
25answers
2k views
23
votes
3answers
2k views
The Path Of The Wildebeest
Golf a program or function which gives the \$n^{\text{th}}\$ location of the wildebeest who starts at square \$1\$ on an infinite chessboard which is numbered in an anti-clockwise square spiral, where ...
24
votes
15answers
3k views
Matrix Jigsaw Puzzles
Input:
An integer n
Two equal-sized square matrices (with their width/height being a multiple of n)
Output:
One of two ...
27
votes
41answers
2k views
Enumerate each series of identical numbers in-place
Given a list of strictly positive integers, go through each distinct number and replace all occurrences of it with successive indices (zero or one based) of a new series.
Examples
...
23
votes
18answers
2k views
Collapsing numbers
Let's define the a function on natural numbers \$n\$, written as base 10 digits \$d_k\; d_{k-1}\; \dotsc\; d_1\; d_0\$, as follows:
As long as there are equal adjacent digits \$d_i\;d_{i-1}\$, ...
